Linux Man Page Viewer

The following form allows you to view linux man pages.

Command:

ssh-keyscan

[host | addrlistnamelist] ...

DESCRIPTION

ssh-keyscan is a utility for gathering the public ssh host keys of a num-
ber of hosts. It was designed to aid in building and verifying
ssh_known_hosts files. ssh-keyscan provides a minimal interface suitable
for use by shell and perl scripts.
ssh-keyscan uses non-blocking socket I/O to contact as many hosts as pos-
sible in parallel, so it is very efficient. The keys from a domain of
1,000 hosts can be collected in tens of seconds, even when some of those
hosts are down or do not run ssh. For scanning, one does not need login
access to the machines that are being scanned, nor does the scanning pro-
cess involve any encryption.
The options are as follows:
-4 Forces ssh-keyscan to use IPv4 addresses only.
-6 Forces ssh-keyscan to use IPv6 addresses only.
-ffile
Read hosts or addrlistnamelist pairs from this file, one per
line. If - is supplied instead of a filename, ssh-keyscan will
read hosts or addrlistnamelist pairs from the standard input.
-H Hash all hostnames and addresses in the output. Hashed names may
be used normally by ssh and sshd, but they do not reveal identi-
fying information should the file's contents be disclosed.
-pport
Port to connect to on the remote host.
-Ttimeout
Set the timeout for connection attempts. If timeout seconds have
elapsed since a connection was initiated to a host or since the
last time anything was read from that host, then the connection
is closed and the host in question considered unavailable.
Default is 5 seconds.
-ttype
Specifies the type of the key to fetch from the scanned hosts.
The possible values are "rsa1" for protocol version 1 and "dsa",
"ecdsa" or "rsa" for protocol version 2. Multiple values may be
specified by separating them with commas. The default is "rsa".
-v Verbose mode. Causes ssh-keyscan to print debugging messages
about its progress.

SECURITY

If an ssh_known_hosts file is constructed using ssh-keyscan without veri-
fying the keys, users will be vulnerable to maninthemiddle attacks.
host-or-namelist keytype base64-encoded-key
Where keytype is either "ecdsa-sha2-nistp256", "ecdsa-sha2-nistp384",
"ecdsa-sha2-nistp521", "ssh-dss" or "ssh-rsa".
/etc/ssh/ssh_known_hosts

SEE ALSO

AUTHORS

David Mazieres <dm@lcs.mit.edu> wrote the initial version, and Wayne
Davison <wayned@users.sourceforge.net> added support for protocol version
2.

BUGS

It generates "Connection closed by remote host" messages on the consoles
of all the machines it scans if the server is older than version 2.9.
This is because it opens a connection to the ssh port, reads the public
key, and drops the connection as soon as it gets the key.